From their website:
Even if your rules aren’t finished, we’re always looking for projects for the future. So, if you have a game that’s almost there, or the seed of a fantastic idea, we’d love to hear from you – feel free to get in touch.
The Osprey Wargames books are 64 pages long – the same as one of our Elite series books – and the word count should be in the 22,000 range. Apart from that, though, pretty much anything goes!
We know there are some amazing homebrew games out there, and we’re looking forward to helping produce them as the high-quality books they deserve to be!
Email firstname.lastname@example.org with any enquiries, and keep watching this space for more news.